In an electroforming apparatus of a type described above, it is customary to provide a nozzle means in a space between a rotatable cathode platen or disc adapted to support a moulding tool blank and an anode basket for ejecting an electrolytic fluid uniformly onto the blank to be coated. Accordingly, the spacing between the cathode platen and the anode basket is basically determined by the amount of space required for the nozzle means. The electrolytic fluid introduced between the cathode platen and the anode basket serves as a conductive medium for ion migration caused by the electrical potential applied to the anode basket and the cathode platen. Thus, the greater the spacing between the anode basket and the cathode platen, the greater the electrical resistance caused by the electrolytic fluid, this then correspondingly influencing the migration of ions and hence the thickness of the layer provided on the blank that can be achieved per unit of time. On the other hand, the electrical potential cannot be arbitrarily increased for overcoming the electrical resistance since dissolution phenomena will occur at the anode basket above an upper limit of the voltage, e.g. about 20 volts. Accordingly a reduction of the spacing between the anode basket and the cathode platen is principally desirable in order to reduce the electrical resistance between these parts, which would permit higher current intensities for a same value of voltage, resulting in a corresponding shortening of the processing time. Furthermore, a reduction of the spacing between the anode basket and the cathode platen would result in a more uniform distribution in the thickness of the layer.
An object of the invention therefore is to provide an electroforming apparatus having minimized spacing between the cathode and anode assemblies. Another object is to provide an electroforming apparatus having minimized spacing between the cathode and anode assemblies without this being detrimental to the distribution of the electrolytic fluid along the cathode assembly or to the rotation thereof.